DESCRIPTION: (Applicant's Description) Werner syndrome (WS) is an inherited recessive disease characterized by genetic instability and a high frequency of specific types of cancer. The recent identification and cloning of the WS gene presents the opportunity to determine how it functions and how mutations in the gene are associated with genetic instability and cancer. On the basis of sequence homology, the WS gene was predicted to encode a DNA helicase. The applicants have overexpressed the WS protein in baculovirus-infected insect cells and purified it to hear homogeneity. The recombinant protein unwinds double-stranded DNA, translocating in the 3' to 5' direction. The production of active WS protein should allow them to define its function by using in vitro model systems and to further analyze its role in the generation of genetic instability. In order to further characterize the WS helicase activity, the investigators will purify the wild-type and mutant WS proteins to homogeneity. In vitro studies that (1) define substrate specificity, processivity, and stoichiometry, (2) identify interacting proteins and (3) assess involvement in DNA repair, replication, and mutagenesis should provide significant clues to the function of WS protein in cells. In addition, they will search amongst the general population for mutations in the WS gene in particular cancers that are associated with WS. These studies will provide the biochemical foundation for the proposed program project.